The present invention relates to spiral binding machines in general, and more particularly to improvements in a method and an apparatus or tool which can be used in such machines to loop the end portions of outermost convolutions of a spiral wire binder which loosely connects the overlapping sheets of a pad, exercise book, calendar, brochure or a like commodity. Still more particularly, the invention relates to improvements in a method and an apparatus which can be used to loop the end portions of outermost convolutions around the neighboring next-to-the-outermost convolutions of spiral binders which consist of metallic or plastic wire.
U.S. Pat. No. 3,568,729 to Freundlich et al. discloses a complex apparatus which is used to loop the end portions of outermost convolutions across the outer sides, thereupon radially inwardly of and finally across the inner sides of the neighboring (i.e., next-to-the-outermost) convolutions of spiral binders. The patented apparatus can form loops when the machine which embodies such apparatus is operated at a low speed, particularly at a speed which is sufficiently low to permit for manual insertion of spiral binders subsequent to introduction of such binders into the perforations of a note book, pad or the like. However, once the apparatus of the patent to Freundlich et al. is incorporated in a machine which is designed for automatic threading of spiral binders into stacks of paper sheets or the like and for subsequent looping of the end portions of outermost convolutions, the formation of loops is unsatisfactory or the parts of the apparatus break or fail to loop the end portion of outermost convolutions around the neighboring (next-to-the-outermost) convolutions.
U.S. Pat. No. 4,095,623 to Lemburg et al. discloses a different loop forming apparatus which is capable of forming acceptable loops at an elevated speed of the machine wherein the apparatus is installed and which serves to convert a length of wire into a succession of spiral binders which are threaded into the perforations of successive note books or the like prior to automatic looping of portions of both end convolutions on each spiral binder. This is attributed, to a certain degree, to the fact that the apparatus of Lemburg et al. defines a channel wherein the end portion of the outermost convolution is guided during bending and looping to thus ensure that each and every end convolution can be adequately deformed and that the loops into which the end portions of the outermost convolutions are converted assume a predetermined optimum shape, be it in the form of fully closed or in the form of partly open loops which extend along the outer sides of the neighboring next-to-the-outermost convolutions, thereupon inwardly toward the axis of the spiral binder and finally outwardly along the inner sides of the neighboring convolutions. The channel is defined by a turnable loop forming device in combination with a hold-down device which is movable with respect to the loop forming device. The purpose of the hold-down device is to prevent the end portion of the outermost convolution from slipping off an eccentric portion of the loop forming device so that the latter invariably engages and loops the end portion in order to form a loop of desired size and shape. In the absence of the hold-down device, the end portion of the outermost convolution would be likely to slide off the aforementioned eccentric portion because the end portion is of arcuate shape. The apparatus of Lemburg et al. is highly reliable and can make loops of predictable shape on the additional ground that the movements of the aforediscussed loop forming and hold-down devices are properly synchronized with movements of a combined trimming or clipping and bending device which removes the surplus of wire from the outermost convolution of a spiral binder and bends the free end portion of the trimmed outermost convolution so that the end portion is moved into a plane which includes the axis of the spiral binder and such end portion then overlies the outer side of the neighboring (next-to-the-outermost) convolution.
A machine which utilizes the apparatus of Lemburg et al. must be provided with at least one set of apparatus, i.e., with a first apparatus which loops the end portion of one end convolution and with a second apparatus which loops the end portion of the other end convolution of a spiral binder. The dimensions of the combined trimming and bending, hold-down and loop forming devices must be selected with a view to match the diameter of the spiral binder which is to be treated by such devices. If the machine which utilizes the apparatus of Lemburg et al. is to make, insert and loop the ends of larger- or smaller-diameter spiral binders, the two apparatus which are installed in the machine are replaced with a set of apparatus whose devices are designed to trim, bend, hold down and loop the end portions of such different spiral binders. Therefore, each machine which embodies the apparatus of Lemburg et al. is furnished with several sets of loop forming apparatus in order to enhance the versatility of the machine and to thus enable the manufacturer to make, insert and shape the end portions of end convolutions of a wide range of spiral binders including those which are used to loosely connect a relatively small number or those which are used to loosely connect a relatively large number of paper sheets or the like to form articles known as spiral bound steno pads, exercise books or like stationery products.
It is conceivable to furnish each loop forming apparatus of Lemburg et al. with several sets of trimming and bending, hold-down and loop forming devices, i.e., to enable a mechanic or another attendant to convert such apparatus for the looping of end portions of outermost convolutions of large-, medium- or small-diameter spiral binders. However, such conversion of loop forming apparatus would consume much time; therefore, the previously described solution according to which the spiral binding machine is furnished with two or more sets of loop forming apparatus is considered to be more acceptable to the manufacturers of spiral bound note books or like commodities. Furthermore, convertible loop forming apparatus would have to be assembled and dismantled by trained mechanics, and the owner of the spiral binding machine would have to keep in stock a substantial supply of spare parts for each loop forming apparatus.